Known wireless communications devices such as hand-held cellphones and data modems (LANs) typically are equipped with an external wire antenna (whip), which may be fixed or telescoping. Such antennas are inconvenient and susceptible to damage or breakage. The overall size of the wire antenna is relatively large in order to provide optimum signal characteristics. Furthermore, a dedicated mounting means and location for the wire antenna are required to be fixed relatively early in the engineering process. Several antenna assemblies are known, and include:
Quarter Wave Straight Wire
This is a 1/4 wavelength external antenna element, which operates as one side of a half-wave dipole. The other side of the dipole is provided by the ground traces of the transceiver's printed wiring board (PWB). The external 1/4 wave element may be installed permanently at the top of the transceiver housing or may be threaded into place. The 1/4 wave element may also be telescopically received into the transceiver housing to minimize size. The 1/4 wave straight wire adds from 3-6 inches to the overall length of an operating transceiver.
Coiled Quarter Wave Wire
An external small diameter coil that exhibits 1/4 wave resonance, and which is fed against the ground traces of the transceiver's PWB to form an assymetric dipole. The coil may be contained in a molded member protruding from the top of the transceiver housing. A telescoping 1/4 wave straight wire may also pass through the coil, such that the wire and coil are both connected when the wire is extended, and just the coil is connected when the wire is telescoped down. The transceiver overall length is typically increased by 3/4-1 inch by the coil.
Planar Inverted F Antenna (PIFA)
Consists of an external conducting plate which exhibits 1/4 wave resonance, and is fed against the ground traces of the PWB of a transceiver to form an asymmetric dipole. The plate is usually installed on the back panel or side panel of a transceiver and adds to the overall volume of the device.
Patch
Typically consists of a planar dielectric material having a resonant structure on one major surface of the dielectric and a second ground plane structure disposed on the opposite major surface. A post may electrically couple (through the dielectric) the resonant structure to a coaxial feedline.
Additionally, there have been numerous efforts in the past to provide an antenna inside a portable radio communication device. Such efforts have sought at least to reduce the need to have an external whip antenna because of the inconvenience of handling and carrying such a unit with the external antenna extended.